Heating Device

ABSTRACT

The invention relates to a heating device comprising heating elements that are disposed in tubes and bear against contact plates that extend out of the tubes. According to the invention, the tubes are composed of a plurality of extruded parts that are disposed transversely to the inflow direction of a fluid to be heated, and are held next to each other by a holder.

The invention is directed to a heating device of a type known from DE 10 2006 018 784 B4.

In the case of the known heating device, an extruded part is used that includes openings that extend transversely to the extrusion direction and through which a fluid to be heated can flow. The disadvantage of the known heating device is that an additional working step must be carried out on an extruded part to create the openings. The object of the present invention, therefore, is to demonstrate a way in which this effort can be avoided.

SUMMARY OF THE INVENTION

In a heating device according to the invention, several extruded parts are held next to each other by a holder transversely to the flow direction. Advantageously, a fluid to be heated can flow along the extruded parts, thereby eliminating the need for openings that extend transversely to the extrusion direction. In the case of a heating device according to the invention, a fluid to be heated preferably flows in the longitudinal direction, along the tubes formed by the extruded parts. However, it is also possible to design a heating device according to the invention such that a fluid to be heated flows between adjacent tubes transversely to their longitudinal direction. The extruded tubes are preferably single-pieced, but can also be composed of multiple pieces, e.g. be composed of a U-shaped profile or a C-shaped profile and a sealing cover strip.

A heating device according to the invention preferably includes at least one power rail to which a plurality of contact plates is connected. The power rail extends from the contact plates connected thereto to a holder that holds the tubes containing the heating elements. A heating device according to the invention preferably includes a plurality of power rails, each of which contacts contact plates that extend at one end out of tubes situated in a row. The holder preferably comprises a supply rail to which a plurality of power rails is connected. If the tubes are used to provide a ground connection, then a single supply rail is sufficient. Preferably, however, the heating elements are electrically insulated against the tubes and are each disposed between two contact plates. Particularly preferably, these two contact plates extend out of the tubes at opposite ends. In this preferred case, the holder contains two supply rails, to each of which one half of the contact plates is connected. The two supply rails are preferably disposed on the same end of the heating device e.g. on the same frame part.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages of the invention are explained using embodiments, with reference to the attached drawings. Parts that are identical or corresponding are labelled using the same reference numerals. The drawings show:

FIG. 1 an embodiment of a heating device according to the invention;

FIG. 2 a front view of FIG. 1;

FIG. 3 a side view of FIG. 1;

FIG. 4 a view of the heating device from above;

FIG. 5 a view of the heating device from below;

FIG. 6 a further embodiment of a heating device; and

FIG. 7 a schematic depiction of the components disposed in the tubes of the heating device.

DETAILED DESCRIPTION

The heating device shown in FIGS. 1 through 5 comprises several extruded parts 2 that are arranged side by side and held by a holder designed as a frame. The frame is composed of four joined frame parts i.e. an upper frame part 1 a, a lower frame part 1 b, and two lateral frame parts 1 c. Extruded parts 2, which are disposed next to each other in the frame transversely to the flow direction, contain tubes 2 a. Tubes 2 a of various extruded parts 2 are situated in rows. In the embodiment shown, these rows extend parallel to lateral frame parts 1 c.

In the embodiment shown, each extruded part 2 includes five tubes 2 a in which heating elements 7 are disposed; heating elements 7 are shown in FIG. 7. In the figures, only one tube 2 a of each extruded part 2 can be seen in each case since remaining tubes 2 a are covered by power rails 3 that contact contact plates (not depicted) that extend out of tubes 2 a.

Preferably, heating elements 7 in tubes 2 a are each disposed between two contact plates 8 that are electrically insulated against tubes 2 a and extend out of tubes 2 a at different ends. It is also possible, however, for each heating element 7 to contact only a single contact plate 8 and to form a ground connection via extruded parts 2.

Power rails 3 can be designed as plastic-enclosed sheet-metal strips. The sheet-metal strips are preferably coated with a plastic jacket. The plastic jacket can also be slid onto the sheet-metal strips. The plastic jacket of the contact rails can have openings in a few places to facilitate the contacting of contact plates which extend out of tubes 2 a. The contact plates are preferably bent at their ends. For example, the contact plates having bent ends can bear resiliently against the power rails. It is also possible to bend tabs out of power rails 3, that bear against the contact plates.

Power rails 3 extend transversely to diametrically opposed frame parts 1 a, 1 b and, in the embodiment shown, plug into frame parts 1 a, 1 b. The heating device is therefore easy to assemble. However, it is not absolutely necessary for power rails 3 to extend from one frame part la to a diametrically opposed frame part 1 b. It is also possible for power rails 3 to terminate at a distance away from one of these frame parts, e.g. the lower frame part 1 b.

Power rails 3 are connected via the frame to the electrical system of a motor vehicle. For this purpose, power rails 3 extend into upper frame part 1 a, on which at least one supply rail 4 is mounted, and to which a plurality of power rails 3 is connected. In the embodiment shown, contact plates 9, each of which is contacted by one of the power rails 3, extend out of tubes 2 a at both ends. Accordingly, in the embodiment shown, one half of power rails 3 should be connected to positive potential and one half of power rails 3 should be contacted to negative potential. Two supply rails 4 are therefore provided in the embodiment shown. Supply rails 4 preferably extend in the same frame part 1 a, although they can also be disposed at opposite ends of the heating device and, therefore, in diametrically opposed frame parts. Supply rails 4 can carry connection elements 4 a that are designed e.g. as projections that extend transversely to supply rails 4. Due to the connection on diametrically opposed sides of tube 2 a, a large distance between the two terminal potentials advantageously results, thereby increasing safety, especially in high-voltage applications.

The frame can include a printed circuit board 5 on frame part 1 a on which supply rails 4 are installed. Supply rails 4 can be designed as conductor tracks on printed circuit board 5, or they can be designed e.g. as separate pieces of sheet metal, as is the case in the embodiment shown. Printed circuit board 5 can carry one or more power semiconductors 6 for controlling the heating device. Printed circuit board 5 can carry a heat sink 6 to utilize the heat dissipated from power semiconductors 6 or other electronic components disposed on printed circuit board 5.

Extruded parts 2 are fastened to lateral frame parts 1 c e.g. by being plugged in or hooked in. Lateral frame parts 1 c, to which extruded parts 2 are fastened, preferably extend parallel to power rails 3. In the embodiment shown, the frame carries eleven extruded parts 2, each of which contains five tubes 2 a. The number of tubes 2 a per extruded part 2 can be selected freely within wide limits, as can the number of extruded parts 2. In general, it is favorable to have two to five tubes per extruded part, and four to fifteen, in particular six to twelve, adjacently disposed extruded parts.

Extruded parts 2 preferably include heat-dissipation fins 2 b to improve heat dissipation. Heat-dissipation fins 2 b extend out of a base plate. Preferably, heat-dissipation fins 2 b extend on both sides of the base plate. Instead of or in addition to heat-dissipation fins 2 b, it is also possible to use additional tubes 2 a that are not filled with heating elements 7.

Preferably, one contact plate 8 contacts only one single heating element 7 i.e. tubes 2 a do not contain more than one heating element 7 each. However, it is also possible for each contact plate 8 to contact a plurality of heating elements 7, e.g. two to five heating elements, that are disposed one behind the other in a tube 2 a.

Extruded parts 2 can be stacked one on top of the other, and they can touch each other. Preferably, however, adjacent extruded parts 2 do not touch each other, and are therefore disposed at a distance from each other, as shown in the figures. This has the advantage that any manufacturing tolerances of extruded parts 2 can be compensated for by the distances provided between them,

PTC heating elements are preferably used as heating elements 7, that is, heating elements having a positive temperature coefficient that increases abruptly once a critical temperature is reached. Ceramic heating elements are particularly suitable, for instance those based on barium titanate.

Tubes 2 a that contain heating elements 7 are preferably square tubes, as shown in the drawings. After the PTC elements and contact plates 9 have been installed, tubes 2 a can be molded by compression to improve the thermal coupling. To simplify the installation of heating elements 7 in tubes 2 a, it is advantageous to use assembly frames 13 which hold heating elements 7 and contact plates 9. Assembly frames 13 can be slid onto contact plates 9, for example. It is also possible to injection-mold assembly frames 13 around contact plates 9. Assembly frames 13 can include, in particular, receptacles 14 for heating elements 7.

A further embodiment of a heating device according to the invention is shown schematically in FIG. 6. Similar to the embodiment described above, the heating device is composed of several extruded parts 2 that are disposed side by side transversely to the flow direction and are held by a holder 1 a, 1 c.

The main difference from the above-described embodiment is that the inflow direction, which is indicated by arrows in FIG. 6, of the fluid to be heated extends transversely to the longitudinal direction of tubes 2 a and, therefore, transversely to the extrusion direction. Mutually engaged heat-dissipation fins 2 b of extruded parts 2 define a serpentine flow path. Similar to the above-described embodiment, extruded parts are adjacently disposed transversely to the direction of flow.

The heating device is shown in FIG. 6 as viewed perpendicularly to the inflow direction and in the extrusion direction. Power rails 3 and the curved ends of contact plates 8 therefore overlap extruded parts 2. In FIG. 6, power rails 3, holder I a, and contact plates 8 are shaded or appear to be transparent, to ensure that extruded parts 2 disposed underneath them are clearly visible.

Power rails 3 are disposed in holder part 1 a which is situated in the plane of the drawing. Power rails 3 can be connected directly or via a printed circuit board 5.

The plane defined by holder part 1 a and holder parts 1 c is then transverse to the inflow direction shown in FIG. 6. Holder part la that connects the two holder parts 1 c shown therefore extends along the plane in which power rails 3 shown in FIG. 6 are disposed.

In the embodiment shown in FIG. 6, the holder can form a frame. In contrast to the above-described embodiment, the longitudinal direction of tubes 2 a and, therefore, the direction of extrusion then extend in the plane of the frame.

In FIG. 6, two tubes 2 a are shown, one behind the other in the direction of flow, that is, each extruded part 2 includes two tubes 2 a. It is also possible, however, to have more than two tubes 2 a, or a different number of tubes 2 a.

Furthermore, the embodiment shows the arrangement of tubes 2 a in uniform rows. However, it is also possible for tubes 2 a to be offset relative to adjacent extruded parts 2.

Extruded parts 2 are preferably fastened to holder part 1 c by clamping. In that case, holding elements of holder part 1 c clamp with fins 2 b of extruded parts 2.

The layout in tube 2 a is shown in FIG. 7. Each tube 2 a contains two identical contact plates 8, between which at least one square heating element 7 composed of a PTC ceramic (positive temperature coefficient) is disposed. One assembly frame 13 is mounted on each contact plate 8 and defines receptacles 14 for heating elements 7. Assembly frame 13 is preferably composed of plastic and can be slid onto contact plates 8. However, assembly frame 13 can also be injected around contact plates 8.

In the embodiment shown, and as shown in FIG. 7, assembly frame 13 exposes a back side of contact plates 8, which faces away from heating elements 7. Contact plates 8 include an electrically insulating layer 15, which is a strip of Kapton film in the embodiment shown, on their side facing away from heating elements 7.

Ends 9 of contact plates 8 that are connected to power rails 3 are angled. Ends 9 can be fastened to power rails 3 e.g. using rivets or screws.

The layout shown in FIG. 7 can be used for both of the embodiments described above.

REFERENCE NUMERALS

1 a Holder part

1 b Holder part

1 c Holder part

2 Extruded part

2 a Tube

2 b Heat-dissipation fins

3 Power rail

4 Supply rail

4 a Terminal elements

5 Printed circuit board

6 Power semiconductor

7 Heating element

8 Contact plate

9 End of the contact plate

13 Assembly frame

14 Recess

15 Insulating layer 

What is claimed is:
 1. A heating device comprising a plurality of tubes; contact plates extending out of each tube; and heating elements disposed in the tubes and bearing against the contact plates; and wherein the tubes are composed of a plurality of extruded parts that are disposed transversely to the inflow direction of a fluid to be heated, and are held next to each other by a holder.
 2. The heating device according to claim 1, wherein at least one power rail is present, to which a plurality of contact plates is connected, and which leads from the contact plates connected to it, to the holder.
 3. The heating device according to claim 1, wherein the holder is a frame that encloses the tubes.
 4. The heating device according to claim 3, wherein the longitudinal direction of the tubes extends transversely to the plane of the frame.
 5. The heating device according to claim 2, wherein the holder has a holder part to which the at least one power rail leads and which extends transversely to the power rail.
 6. The heating device according to claim 2, wherein the at least one power rail extends between two diametrically opposed holder parts.
 7. The heating device according to claim 6, wherein the at least one power rail is plugged into at least one of the two diametrically opposed holder parts.
 8. The heating device according to claim 2, wherein each heating element bears against two contact plates that extend out of tubes at different ends and are contacted by different power rails.
 9. The heating device according to claim 2, wherein the holder carries a supply rail that supplies the power rails with current.
 10. The heating device according to claim 8, wherein the holder carries two supply rails, wherein one of the two supply rails electrically contacts, via connected power rails, the contact plates extending out of tube ends on one side of the heating device, and the other supply rail electrically contacts the contact plates extending out of the tube ends on the other side of the heating device.
 11. The heating device according to claim 10, wherein the two supply rails are carried by the same holder part.
 12. The heating device according to claim 2, wherein the power rails are designed as sheet-metal strips enclosed in plastic.
 13. The heating device according to claim 1, wherein the contact plates are angled on their end that extends out of tubes.
 14. The heating device according to claim 1, wherein neighboring extruded parts do not touch each other.
 15. The heating device according to claim 1, wherein the extruded parts are plugged into the holder.
 16. The heating device according to claim 1, wherein the extruded parts are fastened to holder parts that extend transversely to the holder part from which the power rail extends.
 17. The heating device according to claim 1, wherein the extruded tubes include heat-dissipation fins.
 18. The heating device according to claim 1, wherein the holder carries a printed circuit board to which the at least one power rail is connected.
 19. The heating device according to claim 1, wherein the extruded parts are held by the holder in a clamped manner.
 20. The heating device according to claim 1, wherein each contact plate carries an assembly frame. 